The present invention relates to a novel process of electrostatic printing, and more particularly to an electrostatic printing process in which an electrostatic printing master sheet or plate having reverse images of a dielectric toner is prepared and a large number of duplicates are produced using the master sheet or plate by repeating electrostatic printing procedures of electrification of the dielectric toner images, development of the images with a toner, transfer of the toner images to a material to be printed and fixing of the transferred images thereon.
In recent years, electrophotography shows marked progress, and many processes have been proposed or put to practical use. There are widely employed a direct process called generally electrofax process in which a photoconductive support is directly electrified, exposed imagewise to light and developed with a toner and the toner image is then fixed; and an indirect process called xerography or plain paper copying process in which a photoconductive, photosensitive body is electrified, exposed imagewise to light and developed with a toner and the toner image so formed once on the photoconductive, photosensitive body is then transferred to a material to be printed and is fixed thereon. There is also known an electrostatography in which an electric signal is directly applied to an electrostatographic paper consisting of an electroconduction-treated support and a dielectric layer to form an electrostatic latent image and then a toner image is formed by development of the latent image with a toner and is fixed.
These electrophotographic processes are suited for production of a relatively small number of duplicates, but not for production of a large number of duplicates at a high speed from the original.
An electrophotographic copying machine called high speed plain paper copying machine capable of reproducing at a speed of 40 to 70 sheets per minute has been lately developed, but there are problems to be solved in reliability and machine cost.
Accordingly, it is a main object of the present invention to provide a process for electrostatic printing suited for making a multitude of duplicates at high speeds.
Another object of the present invention is to provide a process for electrostatic printing which can inexpensively produce a multitude of duplicates with simple procedures.
These and other objects of the invention will become apparent from the description hereinafter.